In female rats given male hormone at birth, sex behavior and other functions of the brain are permanently altered. We propose to examine patterns of hormonally altered RNA transcription and their regional distribution in the brain, as well as normal progressive sex differentiation of transcription and its response to various hormonal environments. In male frogs, sexual clasping and vocalization are behaviors that are readily evoked for analysis in the laboratory under defined conditions. We propose to identify the as yet unknown testicular hormone that regulates this behavior. By lesioning and electrical stimulation we expect to locate the brain center(s) for male sex behavior. By locally implanted hormones (in the brain) and systemically injected hormones we wish to record regionally limited electrical responses of the sex behavioral brain centers and their afferent and efferent nervous pathways. In such animals regional changes in brain RNA transcription also will be studied.